Conformational structures of 3-cyanoindole-(H2O)n (n = 0–2) by UV–UV hole-burning and IR-dip spectroscopy

The excitation spectra of 3-cyanoindole (3CI) and its water clusters, 3CI-(H2O)n (n = 1 and 2), have been measured by mass-selected resonant two-photon ionization and UV–UV hole-burning (UVHB) spectroscopy. The observed spectra are compared with the predictions of ab initio and density functional theory calculations. The comparison suggests that the spectra arise from a single conformer of 3CI and two conformers of 3CI-(H2O)n (n = 1 and 2) each. UVHB and IR-dip spectroscopy were employed to identify the conformers of 3CI-(H2O)1 and 3CI-(H2O)2. The conformation-specific structural assignment of the conformers is compared and discussed with theoretical calculations.